1. Field of Invention
Engine valve stroke adjusting devices.
2. Prior Art
Heretofore attempts have been made to modify the lengths of strokes of the valves of internal combustion engines. In most of these prior structures, the adjustment of the valve stroke necessarily involves a change in the time cycle and relation between the tappet and cam. In one instance, as disclosed in U.S. Pat. No. 1,440,427, issued Jan. 2, 1923, a valve stroke length adjustment which can function with a substantial change in the time cycle is provided. However, in that structure, an individual control is provided for each valve, and each control is arranged to be operated manually separate and apart from the others, to effect adjustment of its associated valve. Furthermore, each control is located in its entirety within the engine immediately adjacent the associated valve it is to adjust, and is very difficult of access. Again, in this prior structure, the line of thrust of the driving connection between the tappet and its associated valve stem must be shifted transversely of the stem and tappet to effect the stroke adjustment. This shift necessarily imposes rocking moments on the valve in addition to those which would normally be occasioned by the conventional driving connection between the valve and its cam. Thus not only are rocking moments from the timing cam transmitted to the valve itself, but also, additional rocking moments inherently are created by the prior control devices themselves, causing undue wear and leading to erratic timing and operation.
In the prior art mentioned, the total lift with a quarter inch cam lift ranges from about 5/32 inch maximum to a minimum of from zero to usually 3/32. Thus the usual operating range of maximum to minimum valve stroke is about 5 maximum to 3 minimum.